Velocity measuring device



Dec. 14, 1937. w. VAN B. ROBERTS V ELOCI'I'Y MEASURING DEVICE Filed Feb. 25, 1933 I-I I AMPLIFIER N 2 INVENTOR- B. OBERTS ATTORNEY- Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE 2.102.166 VELOCITYMEASURING DEVICE Walter van B. Roberts, Princeton, N. J., assignor to Radio Corporation of America, a. corporation of Delaware Application February 25, 1933, Serial No. 658,654

3 Claims. (Cl. 161-18) This invention relates to a device for measura length of time as desired, the reading being ing the speed of a golf ball, especially for the erased before the next operation of the apparatus precise comparison of speeds attained-by succesby a manually controlled button. slve strokes. The object of such a device is to It is another object of the invention to produce 5 provide a means for instructing players in a cona mechanism which will be fully automatic in vincing fashion as to what sort of stroke will prothat a number of strokes may be made in rapid duce the highest ball speed which in turn means succession without any attention or adjustment the longest drive, other things being equal. It is to the recording means, the speed of the ball at well known among golfers that bad results are each stroke being indicated for suflicient length likely to follow when a player makes a strenuous of time to be observed, the indication, however, effort to hit a ball harder than he can do with not occurring until two or three seconds after the a relatively efiortless swing. Most golfers admit ball is struck so as to allow the stroke to be comthe truth of this but paradoxically many of them pleted at leisure before the attention is transcannot seem to believe it. This peculiarity apferred to the indicating means, after which the pears to be something that is just the opposite of entire mechanism of its own accord reverts to its the humorous definition of the word faith as original condition and is ready to indicate the meaning believing what you know ain't so. speed of the next ball struck without any adjust- That is, the golfers know that pressing is usually ment or resetting of any of its parts. Prefaccompanied by inferior results but they fail to erably, the device of this invention is to be used believe that the best results can be obtained with in connection with one of the automatic teeing relatively little eifort properly applied. The machines at present on the market, which maaverage golfer who is fortunate enough to hit chines include a hopper to hold a large number a number of drives cleanly and well will begin of balls and a trigger arrangement, the actuation to say to himself now that I am hitting them of which, releases one ball and allows it to roll right I will put a little more beef into it and out of the machine and into position on a rubber get a whale of a drive. When he does this, tee of suitable height for driving. With this however, his game will probably go to pieces. preferred combination the pupil may strike ball Therefore, the object of this invention is to proafter ball with the minimum of interruption bevide a mechanism for use by the professional in tween shots and thus retain in his mind the connection with his teaching work which will feel of each stroke together with the resulting enable him to demonstrate to the pupil that the ball speed and hence rapidly learn the proper properly executed and relatively effortless stroke feel for the best results. actually produces a greater ball speed than In the drawing, strokes involving great conscious exertion even Fig. 1 illustrates schematically one embodiwhen the ball is squarely hit with one of these ment of the present invention utilizing thyratrcns strokes. Of course, it is possible for a golfer to to control the charging of a condenser -arcome to the same conclusions as a result of drivrangement; ing a large number of balls from the tee, but in Fig. 2 illustrates another modification of the this case it is dificult to tell which of the balls invention which is entirely automatic; and,

really starts the fastest as the distance travelled Fig. 3 is another modification of the invention depends considerably upon the nature of the soil wherein the circuits are somewhat simplified. where the ball hits and the trajectory etc. so that Referring particularly to Fig 1 there is shown only by observing the average results of a numa player I about to drive off. As pictured, the ber of strokes can any conclusions be reached. player is about to swing his club 3 and hit the In contrast to this the present invention requires teed ball 2 against the screen 20, the path of only a single well hit shotto establish a value the ball is shown by the dotted lines. A microof ball speed which can be obtained with a proper phone 4 connected to the usual microphone cirstroke and then the player need only make cult comprising a source of current 5 and the one well hit shot involving great conscious efprimary of an audio transformer 6, is located fort to demonstrate that no greater speed can be adjacent the teed ball 2. The microphone is attained. preferably provided with a reflector which con- It is an object of the present invention to procentrates sound from the impact between the club duce a mechanism which will be fully automatic and the ball at the microphone. A similar microto indicate visually a reading indicative of the phone ll connected to the usual microphone cirball speed and retaining the reading for as great ult compr current Source 22 and Pr ry f ha -1 an ins anode current source 9, switch 21, resistances t is amazes insformer 231s located preferably directiy berid the screen 28.. repair of thyratron tubes and i8 having input and output circuits are ranged so as to be respectively aflected by the .crophones 4 and ii. The input circuit of oyratron 8 comprises a variable biasing source and the secondary of transformer 6 while the put circuit of thyratron [8 includes variable ising source 2| and the secondary of transform- 23. The output circuits of both the thyrainclude a common portion comprisit is provided which includes the normally open itch 26 and resistance 24. A spring con-trolled sh-button -25 is arranged to cooperate with itches 21 and 26. Depressing the push-button ens switch 21 and closes switch 26 for purposes be hereinafter pointed out.

The operation of thesystem shown in Fig. 1 as follows:- Microphone 4 which, as previously stated, is

. :ated preferably close to the ball 2, responds to a sound emitted when the club 3 comes incon- :t with the ball. The sudden change in micro- ,one, current will (if the polarity of the transrmer B is correct) kick the grid of thyratron in a positive direction and thus start current th is thyratron. Part of this current flows rough solenoid II and thus closes-contact l2 owing condenser I3 to charge through resist- I ca 1.6.. About a 20th of a second laterthe sound the ball 2 hitting the screenZflsimilarly starts iyratron I8 and thus neutralizes the current the solenoid II and switch I2 opens by means gravity or a suitable spring. (If the relay is larized the second thyratron current can be ranged to have a greater effect than the first so it the magnet pull reverses in direction when a second thyratron starts.) Resistance l8 res capacity I3 is chosen so as to have a time istant which is approximately equal to A, of second so that the voltage to which I3 is arged will be approximately proportional to 2 time of flight of the ball and is indicated by ctro-static voltmeter l4. After the reading of has been noted the machine is restored to its ginal condition by pressing button 25 which charges condenser l3 in a non-oscillatory lhion through resistance 24 and also breaks 2 plate circuits of the two thyratrons 8 and so as to stop the "thyratron currents. The :tem is then in condition for another drive. should be understood that if necessary suite amplifiers may be provided between the two :rophone output circuits and the associated lyratron input circuits.

In Fig. 2, the system up to the transformers 6 :l 23 is the same as described above in connecn with Fig. 1. The secondary of the transmer 6 forms part of the input circuit of an plifier 29 which is identified as amplifier No. The output of the amplifier 29 includes the mary of transformer 38, the secondary of ich forms part of the input circuit of the tubes and 31. These two tubes are connected with ir respective circuits arranged so as to form a sh-pull rectifier arrangement wherein grid conisers 33 and 32 are provided in combination with the respective leak resistors 34 and 38, the output of the devices 35 and 3'! includes the source of space current 38 and the coil of a solenoid 39.

The output of the microphone i1 is transferred to the input of amplifier 28 which is characterized in the drawing as amplifier No.2. The output of amplifier 28 is coupled to the input'of a second push-pull detector arrangement through the transformer 31. This second push-pull detector arrangement comprises a pair of tubes 53, 54 with their respective grid condensers 58 and 51 and leak resistors 55 and 56 respectively. The common output circuit of the tubes 53- and 54 comprises a source of space current 52 and the coil of a solenoid 41 Solenoid 39 which is in the output of the first push-pull detector circuit is arranged so asto operate the spring control switch the latter is adapted to cooperate either with a stop 48 or a contact clip 4|. The solenoid 41 is arranged so as to control the switch blade 58 which in turn is provided with aspring 46. Cooperating with the blade 58 are two contacts 49 and 48. A connection is provided between the switch .blade 58 and contact 4l'which includes a resistance 45 and a condenser 44 in series. A conductive connection is provided between the contact 48 and contact 4|. Between the contact 49 and the switch blade 5i are connected in series a source of current 42 and a ballistic galvanometer .43. The operation of the system shown in Fig. 2

is as follows:-

Sound arriving at the microphone 4 due to the impact of the club 3 on the ball 2 is amplified if necessary by means of the amplifier 29, the output of which is impressed upon the push-pull rectifier tubes 35 and 31. -The values of the grid condensers 33 and 32 and the leak resistors 34 and 38 are so chosen that immediately upon voltage being impressed upon the input of the two rectifier tubes the grid potential becomes negative and remains negative for an interval of time of the order of magnitude of a th of a second, whereby the current through the winding of solenoid 39, which as previously stated is in the output of the tubes 35 and 31, is of an abnormally low value for a 10th of a second or so.

Immediately upon the dropping of the current through winding 39 the armature 5lis drawn away from back-stop 48 by the action of the spring and over against contact 4| thus closing a circuit through ballistic galvanometer 43, contact 49, armature 58, high resistance 45, large condenser 44, contact 4|, armature 5| and the battery 42.

About a twentieth of a second after the ball has been struck, however, it hits a screen 28 and the resulting sound is picked up by microphone II, amplified if necessary by amplifier 28 and impressed upon the input circuit of the push-pull pair of rectifiers 53, 54. Grid condensers 51, 58 and leak resistors 56, 55 have values such that a current through solenoid 41 will remain abnormally small for a period of considerably more than a tenth of a second say in the order of several seconds. As soon as the current through 41 is diminished, spring 46 pulls armature 58 away from contact 49 and over against contact 48. By pulling this armature away from contact 49 the circuit through the galvanometer 43 is opened and thus current has only been allowed to flow through the galvanometer during the interval between the striking of the ball 2 and the ball striking the screen 28, although it is not essential that this interval be exactly the same as the time of flight of the ball because any additive whit tilll'w'ii Ii constant due to slugglshncas in tho rcctlllcra or time of travel of sound to the microphones will not affect relative values of resulting speed but only the absolute values. The ballistic galvanom- 5 eter 43 is chosen to have a rather slow period so that its deflection which is determined by the length of time during which the circuit is complete, will not reach its maximum value until 2 or 3 seconds after the ball has been struck. It will be noted that the contact of armature 50 against point 48 discharges condenser 44 and thus prepares the condenser for the next cycle of operation. ,As described previously, the armature 5i will fallback into its normal open circuit position before the armature 50 falls back into its normal position so that there will be no secondary charging of condenser 44. Thus, stroke after stroke may beplayed within a few seconds of each other without any attention to the mechanism.

Figure 3 shows a somewhat simplified modi-.

' fication of the device of Figure 2. The difference in this case consists in using a single rectifier tube in combination with each microphone and connecting a single relay winding difierentially to the plates of these two tubes each of which is fed with direct current through a high impedance.

In Figure 3, the system shown in similar to the system of Figure 2 up to and including the transformers 3i) and 3|. The output of amplifier 28 feeds into the input of rectifier tube 63 through .the coupling transformer 3|. The input of tube 63 includes the grid condenser 59 and the leak resistor 62. The output of amplifier 29 feeds into the input of rectifier tube 64 through the cou- 3 pling transformer 30. The input of tube 64 comprises grid condenser 60 and leak resistor 6i.

Tubes 63 and E i are arranged-so as to have a common output circuit which comprises a source of space current l6, resistors 65 and 68 and sole- 40 noid 69 the latter being energized by the plate currents. Solenoid 69 is adapted to control a -movable switch blade 15, said switch blade is normally adapted to cooperate with a contact 61 through the pull of spring Ill. A second contact 68 is provided to cooperate with the blade 15 when the solenoid 69 is energized. The two contacts 61 and 68 are connected to each other through a galvanometer Ii and a source of current 12 in series while the blade I5 is permanently 0 connected to one side of the source 12 through a series arrangement of condenser 13 and resistance l4.

The system shown in Fig. 3 operates as follows:--

I'he relay armature i5 is normally held against point 61 by means of spring 10. when the impulse arrives irom amplifier 29 the balance of the two rectifiers is upset and current flows through winding of 69 in such direction as to pull armature 15 over against contact 68 thus starting current to fiow through galvanometer ll. When the impulse from amplifier 28 arrives, however, the

' current through winding 69 is neutralized or reversed in direction thus allowing armature 15 to be pulledback against point 61 thus interrupting the galvanometer circuit at the end of the proper interval and also discharging condenser 13.

It should be understood that the systems disclosed herein and those falling fairly within the 70 scope of the appended claims are not limited to indicating the speed of golf balls and the like but also include tho determination of the speed of any moving body, or the measurement of any time intervals of suitable order of magnitude whose limits are capable of being indicated by electrical impulses.

I claim:

1. In an internal measuring device, a pick-up means responsive to energy waves, a circuit ineluding at least one electronic device coupled to the pick-up means, a relay associated with said circuit, a condenser, a charging circuit for said condenser, means controlled by the relay for initiating a charging action on the condenser, a second pick-up means responsive to energy waves, a circuit including at least one electronic device coupled to the last named pick-up means, a relay associated with the last named circuit, means controlled by said last named relay for stopping the charging action on said condenser and discharging the same and means for indicating the extent of the charge placed on the condenser comprising a ballistic galvanometer having a relatively slow period connected in the condenser charging circuit and adapted to measure the extent oi the charge placed on the condenser.

2. In a small interval measuring device which device may be utilized for the purpose of determining the velocity of a moving mass between two predetermined observation planes, a pick-up means, a circuit including at least one electronic device coupled to the pick-up means, a relay device connected in said circuit, a condenser, a charging circuit for the condenser, means controlled by the relay device acting upon operation to initiate a charging action on the condenser, a second pick-up means, a circuit including at least one electronic device coupled to the second pick-up means, a relay device connected in the last named circuit, means controlled by the last named relay device for stopping the charging action on the condenser and for immediately sub sequently thereafter discharging the condenser means for measuring the charge in the condenser said electronic devices being so arranged as tc restore said relay devices to their original condition after a time interval which is long as com pared to the time interval to be measured,

3. In a small interval measuring device adapted to be utilized for determining the velocity 01 a moving mass between two predetermined observation planes, a pickup means, a circuit including atleast one electronic device coupled t the pickup means, a relay device connected ix said circuit, a condenser, a charging circuit to: the condenser, means controlled by the relay de vice for initiating a charging action on the con denser, a second pickup means, a circuit includ ing at least one electronic device coupled to sail second pickup means, a relay device connected 1] the last named circuit, indicating means to measuring the charge placed on the condenser means controlled by the last named relay mean for simultaneously stopping the charging actioi on the condenser and discharging the same, sai indicating means having a comparatively slot period whereby the charge placed on the con denser is indicated by the. indicating means a1 appreciable interval of time after discharge 0 the condenser. 1

WALTER VAN B. ROBERTS. 

